A New Insight into Catalytic Ozonation with Nanosized Ce–Ti Oxides for NO_<i>x</i> Removal: Confirmation of Ce–O–Ti for Active Sites

Amorphous cerium and titanium mixed oxides (Am-CeTi) and crystalline cerium and titanium mixed oxides (Ct-CeTi), prepared by coprecipitation and impregnation methods, respectively, were successfully utilized in catalytic ozonation for NO_<i>x</i> removal. The catalytic activity has been confirmed to be determined by the concentration of ·OH radicals. Am-CeTi shows higher activity than Ct-CeTi. Ce–O–Ti linkage bonds, with an interaction between Ce and Ti on an atomic scale, are confirmed for the first time to be an active site for catalytic ozonation to remove NO_<i>x</i>. The incorporation of more Ce results in an amorphous structure (Am-CeTi) and a higher number of Ce–O–Ti linkage bonds as compared to that of Ct-CeTi, and the Ce–O–Ti structure is directly observed by HR-TEM. Moreover, such incorporation is responsible for less surface defects and lower densities of surface hydroxyl groups because of the elimination of crystalline defects. The higher catalytic activity of Am-CeTi indicates the small effect of surface defects and surface groups

Hydrothermal Synthesis of Novel Uniform Nanooctahedral Bi₃(FeO₄)(WO₄)₂ Solid Oxide and Visible-Light Photocatalytic Performance

For the first time, novel single-phase octahedral Bi₃(FeO₄)­(WO₄)₂ (BFW) nanocrystals, as a visible-light-induced catalyst, had been successfully synthesized in a facile alkaline hydrothermal way without using any template. Scanning electron microscopy (SEM) images clearly show single crystals of BFW with regular octahedral morphology. The formation of the single-phase BFW compound was recorded using an X-ray diffraction (XRD) technique. The optical property of BFW was investigated using ultraviolet–visible light (UV-vis) spectra. The band-gap energy of BFW was revealed to be 1.98 eV. More importantly, the interfacial interaction of W⁶⁺ ions substituted by Fe³⁺ ions was confirmed. Moreover, the present study pointed out the positions of the valence band and the conduction band. Compared with the Bi₂WO₆ (BW) sample, BFW exhibited superior photocatalytic degradation activity of the Rhodamine B (RhB) under visible-light irradiation. A trapping experiment was conducted to further illustrate that hydroxyl radicals (•OH) played a distinct role among active species during the photodegradation of RhB